K9 Kennel Store double safety door is a great add on for any kennel. This creates a way for small children to feed the family pets without letting your pets escape. This allows you to walk into your kennel and shut the safety door behind you before opening the main door. Compatible With All Our Kennel Systems. Made of a 2" x 4" welded wire construction it looks just as good when installed. The double safety door is very easy to set up in only minutes. So if you would like to add one more element of security for you and your pet the K9 Kennel Store double safety door is the add on for you.